But the real issue I have is that the only reason someone should be deprived the right to keep and bear is if the person is more than likely a danger to themselves or others with a firearm.

I agree in principle, but CA laws make that subject to abuse by the state (as in this case, for example). If a LEO decides, all by himself, to take you in on a 5150 he is required to confiscate your firearms. They can keep them for 30 days, and longer if they petition the court. All of this on the word of a single LEO, no court involvement, no due process. Add the time it takes to get the release forms back from DOJ and you've lost RKBA for a significant amount of time.

If the LEO further claims that you are a danger to yourself or others, and the hospital intake person agrees, you now have a 5-year prohibition, even if they release you a few hours later. The hospital person is likely to 'play it safe' and go along with the LEO. No court involvement, no due process, although the law allows you to petition the court for relief of the prohibition. That takes time and money (pay a lawyer) and not everyone has the means to pay a lawyer.

The restraining order and protective order laws are subject to abuse by the state as well, as judges often grant those based on a claim from a single individual without requiring additional evidence or corroboration. Bang, there goes your RKBA for the duration of the order, plus the additional wait-for-DOJ-release time.